At Day 7, the embryo is lying on its side above the yolk’s

upper surface and the amniotic fluid is visible (Fig. 2H). These positional changes reflect changes in the embryo’s density relative to the density of the EEF and the yolk [4] and [24]. At Day 3, when the vasculature is still forming, it would be advantageous GW-572016 research buy for the embryo to be near the shell to ensure adequate oxygen availability. As the embryo grows and its blood supply matures, it would benefit from the extra physical protection provided by being nearer the center of the egg. The image contrast between different components within the egg changes noticeably during embryonic development. MRI relaxation measurements permit the relaxation times of different regions

within the egg to be investigated. The longitudinal (T1) and transverse (T2) Selleckchem Panobinostat 1H relaxation times of the albumen, yolk, EEF and latebra within the quail eggs were determined during early stages of development and tabulated (Table 1). The T1 and T2 relaxation times of the yolk ranged between 0.34 and 0.42 s and between 24 and 31 ms, respectively, and did not change significantly during development. Egg yolk is an exceedingly complex, microheterogeneous substance [25], and optical microscopy reveals yolk spheres, granules and lipoprotein complexes suspended in an aqueous solution called yolk plasma. The yolk’s insensitivity to 1H relaxation times suggests that its microstructure is quite stable during early development. By Day 2, both the T1 and T2 relaxation times of the EEF are significantly longer than that of the albumen. Hence this EEF has a higher signal intensity (appears brighter) compared to the albumen in the T2-weighted RARE images (Fig. 1C). At Day 3, the T2 relaxation time in EEF and albumen is 197 and 74 ms, respectively. The T2 relaxation time of water in albumen drops significantly from Day 3 onwards so that by Day 6 its relaxation time was below 20 ms. This drop results in the decrease in image signal intensity arising

from the albumen region over time and explains why the albumen in these isothipendyl RARE images appears black by Day 6 (Fig. 1G). Laghi et al. [17] demonstrated in an ex vitro quantitative NMR proton relaxation study of unfertilized hen’s albumen and yolk that there is a direct relationship between the transverse (1/T2) relaxation rate of the albumen and protein concentration. Ovalbumin proteins contain exchangeable protons with very short T2 relaxation times, and the exchange between these protons and water protons reduces the observed water T2 relaxation times in a predictable manner. It is known that the albumen contains a range of different proteins and that their concentration increases significantly during embryonic development [4] and [24]. Thus the major decrease in both the T1 and T2 relaxation times of albumen can be linked to the increase in protein concentration.